May 14, 2020
A new tool allows citizens to measure the carbon storage and health of their local forests—before they are cut down.
FOREST SCIENTIST Dr. Nicholas Coops from UBC and his two colleagues, Dr. Joseph Landsburg (Australia) and Dr. Richard Waring (Oregon), recently won the equivalent of the Nobel Prize in forestry—the Marcus Wallenberg Prize—for their work on an open-source model that allows anyone to predict how their forests are growing in real time.
The tool, called 3PG (Physiological Principles Predicting Growth), can be set up on most computers and will tell you how your local forest is doing and predict what the future might be as climate conditions change. Using available data sets from weather stations that measure temperature, moisture and tree level information from long-term forest plots, coupled with remote sensing data from satellites or LIDAR, we can now answer questions like: How much carbon is being sequestered by this patch of trees? How much carbon was released by that clearcut? How will biodiversity hot spots do in the future? How can we prevent insect outbreaks? How are certain species doing through spring and summer droughts? What if we increase the number of nurse logs in this patch? Is it helping the stressed trees?
The model can be scaled from my tiny patch of forest of 60-year-old Douglas-fir to diverse tracts of forest across the planet. Any student or planner with an interest in forests and climate can adapt the model to local forest data.
It was a tool originally devised for forestry managers to manage plantations, but has much wider applications, according to Coops, including understanding what our Douglas fir forests are going to look like in the future.
To understand why this is hopeful, it is important to start with a refresher on forests and climate change. Currently the only things on the planet that remove carbon dioxide from our atmosphere are plants—either on land, in water or sea. CO2 is sequestered by the forest through everything that photosynthesizes: trees, shrubs, moss, etc and is then processed into carbon which the forest stores in what we call carbon pools: trunks, branches, bark, roots, leaves, shrubs, soil, litter and coarse woody debris (nurse logs, wildlife trees). The plants pull out the carbon and release the oxygen (O2) to the atmosphere. The rate at which they they do that and how they store it, is the complicated part.
Storing carbon depends on complex ecological relationships between species of trees, other plants, lichens and fungi, the soil, the forest litter and detritus, aspect, moisture, temperature and nutrients. It is a big dynamic system and taken at a provincial, national or international level has a great many complexities. At the forest stand level, however, it becomes far more understandable and relevant.
Using the new 3PG tool on my acreage, we assess how each of the different tree species are doing, their height, age and diameter and how much carbon they pull out of the atmosphere on a daily to annual basis and have stored over the last 60 years, and where it is stored.
My forest stores about 1,468 tonnes of carbon dioxide equivalent (CO2e) per hectare (it is actually stored as just carbon but it is expressed as CO2e so we can understand the implications if it is released back into the atmosphere). Two hundred tonnes of that is in the soil, another 200 tonnes in the detritus, about 500 in the trunks/stems and the rest in the branches, bark and shrub layers. Every hectare of my forest is pulling about 14 tonnes of CO2e out of the atmosphere a year.
There is always some natural decaying going on, where the carbon isn’t stored but released back into the atmosphere. This relationship between decay and sequestering is expressed in a figure called “forest growth minus decay.” In a healthy forest like mine, forest growth far exceeds forest decay. In an unhealthy forest where drought decreases the moisture retained in the soil and increases the respiration of carbon back into the atmosphere, that figure can reverse. There are die-offs already starting in my western red cedars on south-facing, dryer slopes so I’m anticipating that these figures will change.
The model works by using key measurements of certain species acquired from long-term research plots, like the ones around southeastern Vancouver Island of coastal Douglas fir forests from old growth to young ones.
Provincial forest ecologist Andy Mackinnon and federal forester Tony Trofymow set up forest plots in 1992 in response to concerns about the effects of clearcutting and the conversion of coastal old-growth to managed forests. The plots provide information about the growth, structure, diversity and carbon storage of forests at different ages, on different aspects, terrains and microclimates. In 2002, research towers were added to fine tune our understanding of fluxes of carbon and water from different pools based on temperature and precipitation. Fluxnet Canada has three forest plots of different aged coastal Douglas fir, one of which is very similar in age and composition to mine, at Oyster River. Pulses of carbon dioxide are measured from processes like soil respiration, decomposition, litterfall and microclimate changes in soil which change with the time of day, the season, and the year. It allows us to attribute specific events and features to fluxes of ecosystem carbon.
The 3PG model is able to apply this information to whichever forest an enquiry directs it to (small to large) by using remote sensing, like satellite and LIDAR.
Finally, it uses climate forecasts to let you ask questions about what it will look like in the future.
Coastal Douglas fir is uniquely suited to these kinds of tools because it is such a wide-ranging tree, from California to Vancouver Island. If I want to know what my forest will look like in a warmer world, the benchmark data from California forests is there to draw from.
The reason this is important is because if you go to the latest (2017) BC Greenhouse Gas Emission Inventory you will discover that over the last 27 years, more than half of all CO2e emissions come from the “Forest Management” sector. Because of a historic federal decision at Kyoto to not include forest management emissions in our inventory, these figures are only included in an appendix. This raises a critical question about how we should respond to these huge emissions and better understand the complex interplay of warming temperatures, greater insect predation, changes in traditional burning practices by First Nations, and modern industrial approaches of salvage clearcut logging. The immensity of the problem requires better tools that can peer right into the different patches of forest and then go back up to 30,000 feet and see the patterns.
To further appreciate the magnitude of the climate crisis as it relates to forestry, remember there are two sides of a carbon equation: on one side is our need to reduce our emissions; on the other is our need to protect and increase our sinks. Ignoring emissions from forestry is a double hit to climate change as we send our emissions skyrocketing while removing our sinks.
And I haven’t even added in another sector that is included in our official inventory called “deforestation,” when sinks are converted permanently to non-forest use. Deforestation emissions take the overall number up another 2.5 million tonnes.
But before we unpack these numbers, remember this story started as good news.
I have been writing about climate change and the problematic forest industry for over 30 years and it has mostly been bad news for climate, wildlife, water, fire and flood risk, and cultural survival. No amount of science seems able to shift governing parties away from the status quo and corporate exceptionalism so what will get us to a different future?
Coops’ colleague, Dr. Gary Bull, head of the Forest Resources Management Department at UBC who has equal international standing in his field of forest policy and sustainable economic models that integrate climate change, indigenous rights and ecosystem services, suggests that 3PG gets us one step closer. Putting a forester’s tool in the hands of local people who love their forests and want to improve their resilience to drought, fire and loss of wildlife is a key part of the solution.
It used to be that only forest carbon scientists hired by companies could calculate these complex carbon equations. This led to a lot of carbon myths, myths that provincial forest ecologist Jim Pojar has done a great job of refuting. (https://sierraclub.bc.ca/7-myths-about-forests-carbon-and-climate-change/ )
If you don’t want to take his word for it, though, now you can see for yourself. With this tool, anyone should be able to figure out that if I clearcut even a hectare of my forest, I will immediately release at least half a thousand tonnes of CO2e from the different carbon pools into the atmosphere through various processes: slashpile burning, increased respiration, and decomposition as the forest floor dries.
In the carbon pool called “trunks,” a good proportion would end up as my firewood, and also go up with the smoke. Some might make it as timber for construction, but the emissions from cutting, trucking and processing it would offset the carbon stored in the few pieces of timber that made it into house beams. Within 15 years, most of the carbon in that hectare of forest would be back in the atmosphere.
I would also have shrunk the world’s carbon sink by a hectare and made adjacent forests more vulnerable to rising soil temperature, wind throw, and fire through loss of moisture in the forest.
Replanting my forest is not mitigation. It will be 17 years before the clearcut is not still emitting carbon. And it will be 105 years before I have even caught up with the storage that I had before I cut it down, if ever.
I could have travelled 250 times to Baja in a jet and still not exceeded those emissions, so why are we not taking these actions into our carbon accounting?
Once you get your head around your own local forests, it is much easier to scale up and make sense of the provincial numbers. In the BC inventory, decomposition from clearcutting accounts for 42,034,000 tonnes (this is probably conservative). Slashburn piles account for another 3,990,000 tonnes. Then there is the big whammy for 2017 of wildfire—176,550,000 tonnes. (Spread over the last 27 years, emissions from fires average out to 20,000,000 tonnes a year.) Wildfire is a bit of misnomer because within this category there is no distinction between fires that burn in unlogged forests and fires that burn through clearcuts, but are not technically accounted for under slashburns. An Oregon State University study found that the 2013 Douglas Fire took off when it “hit a sea of clearcuts.” It makes sense, as the driest tinder for any fire is in a clearcut. They are now called “clearcut firebombs” in the research parlance. (See David Broadland’s The Forest-Industrial Complex’s Molotov Cocktails)
Having a fine-tuned tool that can operate with local data is critical to discern exactly what’s going on.
This forest on Quadra Island is slated to be logged, but its carbon sequestration capacity, critical to global efforts to reduce emissions, has not been taken into consideration by government when it determined the area could be logged. Now local citizens will have a tool that allows them to do the carbon calculation and add another science-based argument for conservation.
Bull points out that these new tools and forest research typically take at least a decade to translate into policy, “but,” he adds, “we could adapt pretty damn quickly if we had the political support, legislation and resources to devolve more power and tools to local communities and First Nations.” He has long believed that the path to climate change mitigation and reconciliation of First Nations land issues is through ensuring the economic benefits flow to those that tend the forests. He is working on innovative economic streams from forest stewardship.
The development of open source tools such as 3PG brings down the biggest obstacle in the past: the costs of planning, management and inventory. For communities and regions to assess alternative economic models for rural communities, the right set of tools in the toolbox is critical. Bull states, “Dr. Coops’ tools are essential.”
Coops is enthusiastic about the potential for the model as it puts a free tool into the hands of local people which is the scale that forest management is best done at. Because it is open source, it can be adapted and developed to reflect the amazing research that has gone on already.
One of the improvements Coops hopes to see in the tool, is a way to improve measuring the below-ground carbon and fuel loads across clearcut landscapes. Coops believes this is possible using drones and satellite imagery. He and Trofymow also examined and compared methods for estimating the amounts of woody residues left after harvest of one of the long term forest plots. In 2017, Trofymow remeasured (after 25 years) the carbon in aboveground forest and woody debris on the four east Vancouver Island sites; soils were remeasured in 2019 and are currently being analyzed. The results will be ready in a year or two.
3PG is currently the most widely-used forest growth model of this type in the world, but not here in BC. Asked what his ultimate dream for the model is, Coops responded: “I want to alert citizens about how they can take care of their forests/carbon sinks.”
See https://3pg.forestry.ubc.ca/software/ for the 3PG software tools.
Briony Penn is the award-winning author of non-fiction books including The Real Thing: The Natural History of Ian McTaggart Cowan, A Year on the Wild Side, and, most recently, Following the Good River: the Life and Times of Wa’xaid, a biography of Cecil Paul (Rocky Mountain Books).